CSR Experiment 2 : WinLink images
Before someone emails me, I don’t care for Pactor or VARA. I don’t mind others using them, however I’m choosing not to support closed modems that are against the spirit of amateur radio.
One thing I alway want to do is post pictures of our journeys online while they are happening. For the CSR this is challenging as there is no cell coverage. From a commercial solution point of view the best way one might be able to do is getting a satellite data service. Not even Starlink operates out this way yet.
On amateur radio there’s a service called WinLink which operates much like email. You can even add attachments. My plan was to use this to build a WinLink to Twitter gateway that would post the images I upload to WinLink onto my Twitter account.
The only problem is that HF doesn’t have a huge amount of bandwidth, WinLink stations over this side of the country don’t exist, and ARDOP is slow (and seemingly buggy with large files).
The solution is to send heavily compressed and resized images. For this I developed HAVIF (headerless AVIF). This crunches the images down to something close to 2.5KB - making them quicker to send and less likely to end up with corruption.
Even though the selection of Winlink stations over this side of the country was poor, I was still able to post several images across the trip. Often I found myself using New Zealand station ZL2SEA to transmit the images.
I wish there were close stations in Western Australia are using the east coast stations were painfully slow and unreliable. When we tested the system on road closer to the east, we were able to post and retrieve messages much much faster and more reliably.
Here’s an example of one of the compressed images.
Other examples removed due to Twitter dieing.
Software and radios used
We used the IC-7100 radio along with a Codan 9350 auto tuner, allowing us to check Winlink while on the move across multiple bands.
Pat, rigctld and ardopc were used to provide a completely opensource and Raspberry Pi compatible solution. Some unit files were created so that radioconsole could be used to automatically configure the services and radio for use easily.
The system generally worked well with many pictures being uploaded along the trip, though it often took finding the right station at the right time of day due to the distances involved. One frustration however was even on good quick paths Winlink CMS would timeout authenticating our requests and sometimes the stations that these were occurring on were our only available options.
You can see all the results here.